The top one is cool. It is stamped metal, which makes it cheap to make. The problem being it is hard to add any threads, bearing seat etc. the plastic insert thing is a real novel solution. I have been a fan of this for a while and cheap Chinese yoyos were the first I saw it on. In the stainless whistling yyf yoyo we worked with a vendor to get the seats (more) precise and added the option of a large bearing pad response, making it interchangeable.